Hydraulically operated devices to accomplish work, such as well drilling, earth boring, pumping, the cutting of metals or other solid materials, and hammering or milling operations, whether above or below water, normally utilize a rotating shaft, or in some cases a reciprocating shaft, mounted within a housing and supported by thrust bearings to drive the drill bit or other tool. The bearings are preferably lubricated by a lubricating material other than the ambient materials utilized to drive the shaft, such as the conventional drilling mud utilized to power a downhole motor driving a drill bit. Where a lubricant, such as grease, is used, the sealing of the lubricated bearings from infiltration of foreign matter as well as the drilling mud or other fluid being transported has been a frustrating and costly problem. While newly developed lubricants which are resistant to flowing water have been helpful in a limited way, as have improved sealing materials and seal designs, the seals are costly and form a fragile sealing system except perhaps when handling abrasive free fluids which are highly lubricous. The net result has been that the useful life of the bearings and seals have been limited, their life expectancy usually being in the neighborhood of 100 hours or less depending upon the contaminants which are encountered.
A potential solution of these problems as well as the problems caused by leakage through the seals and the lubricated areas is to replace the usual lubricated bearing area having seals at both ends with a "no passthrough" system wherein there can be no infiltrating flow of fluids irrespective of pressure drops between the seals in one direction or the other to wash out lubricants and introduce foreign matter. Such "no pass-through" arrangements contemplate the maintenance of balanced pressures on opposite sides of the seals, and while such systems have been tried, they have not been satisfactory due to the inability to maintain balanced pressures on the seals during operation. As a result, such arrangements are short in life and have not solved the basic problem of increasing the useful life of the bearings and their seals.
In contrast to the foregoing, the present invention provides a unique sealed bearing system wherein the bearings are contained in sealed pockets which entrap the lubricant and effectively resist the infiltration of the pockets by contaminants, resulting in greatly enhanced useful life and reduced replacement costs.